Banda Aceh – At least four people have been killed and three badly wounded in the latest violence to hit the restive Indonesian province of Aceh, the military and residents said Wednesday.

Three civilians were killed and three critically wounded after a group of armed men attacked a plantation at Sultan Daulat in the district of Aceh Singkil late Monday, said South Aceh military commander, Lieutenant Colonel Agus Permana.

"The incident started with the arrival of some 20 people armed with rifles in the plantation area. They immediately started to fire at residents, killing three people and critically wounding three others," Permana said. Permana accused separatist rebels of the Free Aceh Movement (GAM). Local GAM leaders could not immediately be reached for comment.

The body of a man with gunshot wounds was found in a ravine at Tapaktuan in South Aceh late on Tuesday, a humanitarian activist there said. His identity remains unknown.

GAM rebels have been fighting since 1976 for an independent Islamic state in the resource-rich province on the northern tip of Sumatra island. More than 1,500 people have been killed in Aceh this year alone, most of them since the government launched a military operation in April.